Vapor phase growth is employed in various areas of the industry world today. Needless to say, it is required for this vapor phase growth that a thin film grown on a wafer has a uniform thickness, composition, and doping concentration throughout the plane thereof. In order to unformalize in-plane film thickness and the like, various possible methods to be used are considered. Among them, a technology to achieve uniform temperature of a wafer when the wafer is heated, is the most important factor.
FIG. 5 is a cross-sectional view showing a construction example of a typical conventional vapor phase growth apparatus. As shown in FIG. 5, a vapor phase growth apparatus 100 includes a reactor 1, a wafer holder 3 on which wafers 2 are placed, a susceptor 4 on which the wafer holder 3 is mounted, a heater 5 provided below the susceptor 4, a rotation mechanism 6 which rotatably supports the wafer holder 3 and the susceptor 4, gas inlet pipes 7 through which raw material gas or carrier gas is supplied, a gas exhaust pipe 8 through which unreacted gas is exhausted, and the like.
FIG. 6 is enlarged views showing construction of the wafer holder 3 in detail; (a) is a plan view, and (b) is a cross-sectional view taken along the line A-A of (a). On one side of the wafer holder 3, a plurality (6 in FIG. 6) of circular pocket holes 3a are formed along the same circumference, in which wafers 2 are placed, and on the other side, the wafer holder 3 is in contact with the susceptor 4.
Note that the susceptor 4 is made of a material having high thermal conductivity (for example, molybdenum and the like) in order to transfer heat from the heater 5 uniformly. It is also typical to use graphite or molybdenum having high thermal conductivity, for the wafer holder 3.
In the vapor phase growth apparatus having the above construction, by heating the bottom of the susceptor 4 using the heater 5, heat is transferred to the wafers 2 via the susceptor 4 and the wafer holder 3 so that the wafers 2 reach a predetermined temperature. In addition, by rotating the susceptor 4 at a predetermined rotating speed using the rotation mechanism 6, vapor phase growth of a thin film is performed while supplying raw material gas and carrier gas that has been introduced from the gas inlets 7 onto the surfaces of the wafers 2 uniformly.
Further, in FIGS. 5 and 6, the wafer holder 3 on which the wafers 2 are mounted is made from a single member. However, when a plurality of wafers are mounted, there is a proposed vapor phase growth apparatus in which a plurality of wafer holders are provided to correspond to a plurality of wafers mounted thereon, and the plurality of wafer holders are mounted on predetermined positions of a susceptor. (For example, see Patent Document 1). Patent Document 1: Japanese Patent Laid-Open Publication No. Heisei 11-8119